After the majority of the world went crazy (unprecedented crazy, by the way) for the HP Touchpad after it dropped its value to $99.99, I got very curious. Obviously the HP Touchpad was sold at a loss, but is it possible to build a somewhat decent tablet (Multitouch capacitive screens, 10" screen, speedy ARM processor, 8+ hr battery life, etc.) for that price, or even less?

Note that this is targeted at consumers, but built by EEs or wannabe EEs (like me). Also, I should mention that I'm referring to the "slate" tablet, not the laptop to PC tablet (although we may see some more of those in the future due to Windows Cool.

So, sourcing parts from Mouser and Digikey, let's see how feasible it is to make a tablet! Smile

Requirements:
1) Multitouch, capacitive touch screen. Yes, we've had this discussion before, but after getting a printer with a resistive touch screen, and playing around with tablets that use resistive touch screens, I can't say that I'm a fan of them. They all require a certain amount of pressure, vs. a simple touch.
2) LCD/(O)LED screen or similar with IPS, around 8" size. IPS is a must for such a tablet, since the screen is usually held or looked at indirectly (i.e. not parallel to your face).
3) Good battery life - at least 8 hours of regular use. Should be more if possible.
4) Good ARM CPU - should be at least 1 GHz.
5) Lots and lots of memory - at LEAST 512 MB.

#4 and #5 can be in form of a development/prototype/hobbyist board.
alberthrocks wrote:
but is it possible to build a somewhat decent tablet (Multitouch capacitive screens, 10" screen, speedy ARM processor, 8+ hr battery life, etc.) for that price, or even less?


No.

Quote:
2) LCD/(O)LED screen or similar with IPS, around 8" size. IPS is a must for such a tablet, since the screen is usually held or looked at indirectly (i.e. not parallel to your face).


If you are on a budget IPS is out. You can get away with cheaper panels on tablets, a number of commercial tablets use non-IPS panels, it's not great and but it's not terrible. IPS here is a luxury.

Quote:
3) Good battery life - at least 8 hours of regular use. Should be more if possible.


Bigger batteries add weight and cost more.

Quote:
4) Good ARM CPU - should be at least 1 GHz.


Dual or single core? Cortex A8 or A9?

Quote:
5) Lots and lots of memory - at LEAST 512 MB.


512MB does not count as anywhere close to "lots and lots". There is a very, *VERY* good reason that pretty much every tablet on the market is 1GB. Consider 1GB your minimum for a sane experience.
I tend to think that you're right about the memory, Kllrnohj, but I'd prefer if you motivated your point about there being a "very good reason" by explaining what that reason actually is. Why can't we get by with 512MB and reduced visual hoopla?
I was once repairing 5 computers at once with a group of friends, and we were going to consolidate the best parts into one machine. When we laid out all the RAM to pick the best, a friend of mine found one that was 256 kilobytes. We used it as a screwdriver.
EDIT: Realized the value was wrong after some consideration
KermMartian wrote:
I tend to think that you're right about the memory, Kllrnohj, but I'd prefer if you motivated your point about there being a "very good reason" by explaining what that reason actually is. Why can't we get by with 512MB and reduced visual hoopla?


After you take chunks out for all the reserved blocks (including the GPU, which has to share system RAM after all and typically gets a carve out), you really don't end up with all that much left over. On a Xoom running Honeycomb, there is actually only ~730mb available to the system (MemTotal in /proc/meminfo), and after a fresh boot there is only 300mb free. Keep in mind you don't have a swap file. You run out of RAM and that's it - you're dead in the water.

"visual hoopla" doesn't really matter here. You need to hardware accelerate the UI of a tablet because the memory bandwidth just isn't there for software rendering (this is going to be especially true on cheaper, lower end SoCs - which are required to hit the $100 mark). Hardware acceleration takes more memory - in some cases a *LOT* more. For example, in Honeycomb hardware acceleration typically adds ~8mb to each process, and Browser will use up to 60mb more just because of hardware acceleration.
http://www.reghardware.com/2011/08/27/ten_budget_android_tablets/ many of these are in the 100 euro range, so a bit more than what alberthro was asking for and it seems most of them are UK only but I'd say that it is indeed possible to build the tablet he desires judging from this list. What I also find interesting is all but one of the listed tablets had 512MB or ram, the odd one out having just 256MB and the review mentions that it was clear that it was lacking.
TheStorm wrote:
http://www.reghardware.com/2011/08/27/ten_budget_android_tablets/ many of these are in the 100 euro range, so a bit more than what alberthro was asking for and it seems most of them are UK only but I'd say that it is indeed possible to build the tablet he desires judging from this list. What I also find interesting is all but one of the listed tablets had 512MB or ram, the odd one out having just 256MB and the review mentions that it was clear that it was lacking.


Really? Did you actually look at that list at all? The 99 is complete garbage and meets nothing alberthro wants. The 119 one is almost sane, so let's take a look at it.

Let's start with the OK/not terrible:
512mb RAM - will be lacking
7" smaller than alberthro wants
Cortex A8 1Ghz - actually not bad. Not good, and will be a lot slower than other tablets, but not terrible
"capacitive screen" - don't mention if it's multitouch, I would actually assume at least pinch/zoom is doable
Definitely not IPS or OLED
4GB of storage is on the low end, but enough for apps

Now the bad:
800 x 480 resolution - ouch. This is going to look pretty bad
Rated for 3 hours of general use battery life
Multitouch is unknown - likely only pinch/zoom capable.

And here's the kicker - 119 is $185.
Kllrnohj wrote:
And here's the kicker - 119 is $185.

Bear in mind that UK technology prices are quite often calculated by taking the dollar amount, sticking a pound sign on the beginning and sometimes adding a bit.
  
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